Computers are used for many purposes. In order to increase their potential capabilities, computers are often equipped with expansion slots. Expansion slots allow expansion cards to be inserted into the computer such that the circuitry of the cards becomes part of the overall computer system. Expansion cards can add such things as more memory, specialized interfaces for the control or monitoring of external equipment, circuitry for improved sound, circuitry for data communications, and many other capabilities that can be desirous in various applications. In order to add an expansion card to a system, the card is typically inserted into an expansion slot and then mounted to the chassis of the computer with a mounting bracket. The mounting bracket typically couples to the rear of the computer chassis, and may include apertures for allowing connections to the expansion card from external to the chassis.
As technology continues to evolve, computers progress to new and different designs. One of the challenges of producing expansion cards is making them compatible with as many different computer designs as possible. Computer manufacturers often standardize certain aspects of the expansion slots such that interoperability of expansion cards is encouraged. For example, the connectivity of the expansion slots can be standardized in terms of the number of pins and the ordering of the pins. The maximum physical dimensions and power consumption of the expansion cards are also often standardized.
A particular problem is presented when the standard maximum size of an expansion card is reduced. When the size of a computer chassis is reduced in terms of height, the maximum height of expansion cards is also reduced. Thus, older cards designed for the larger chassis are not compatible with the reduced-height systems. However, if the expansion slots in the reduced-height systems retain the other physical dimensions and electrical characteristics of the older chassis, shorter cards designed for the reduced-height systems can be used in those with the older, larger chassis design
The ATX and NLX motherboard form-factor specifications describe the mechanical and electrical specifications for building a motherboard and the design considerations for developing a chassis to house the motherboard. The ATX form-factor is older and has larger dimensions. The NLX form-factor is the more recently introduced of the two and is designed for reduced-height expansion cards. Many ATX form-factor machines continue to be used and built, and it is desirable for NLX form-factor expansion cards to be functional in older ATX systems.
In some cases, the base, or main body portion of the expansion card does not provide enough circuit board area to house all of the circuitry that a user might like to have on an expansion card. In other cases, analog circuitry such as TV tuners may be desired on the expansion card. Circuitry of this type is often sensitive to the large amount of noise that can be injected into power and ground sources by digital circuits that are present on the expansion card. In addition to this, multiple connectors on the expansion card may be desirable such that interaction with multiple external circuits and systems is possible.
Consequently, a need exists for an expansion card that promotes interoperabihty with different chassis designs, allows for expansion of the circuit board area of the base portion of the card, has the ability to isolate noise-sensitive components, and supports multiple connectors in a cost-efficient, effective manner.